Hi,
I am trying to get a better understanding of different receiver blocks.
In the ais-tools-gnuradio-1.0.2
(Automatic Identification System (AIS) using GNU Radio - Fun With Electronics)
source code (aisrcv-usrp.py), once symbols are mapped to bits after
demodulation and symbol clock recovery the signal is sent to the
following
blocks:
gr.diff_decoder_bb() and ais.invert10_bb()
I suppose gr.diff_decoder_bb() is a differential decoder and
ais.invert10_bb() only inverts bits (a 0 becomes a 1 and inversely). Am
I
wrong?
I have done some documentation research on AIS and the signal is NRZI
encoded before modulation. I don’t understand how these blocks perform
NRZI
decoding. Can someone please give me a brief explanation?
Thanks,
Irene
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